Seite - 81 - in Water, Energy, and Environment - A Primer

feet for coalbedmethane.Current annual global consumption of natural gas is about 130 trillion cubic feet. My feelings about shale gas (and oil) fracking are mixed. It represents a large, new fossil fuel resource but may present serious environmental concerns.Here is how I see the issues: • Wells drilled into gas-rich shale deposits are usually quite deep, well below the underground aquifers supplying freshwater. • The quantities of water required are large (millions of gallons perwell) and create a hugedemandon localwater supplies. • Major problems with fracking occur when the injected water is returned to the surface and has to be cleaned up or disposed of. Here is one place where extraction companiesmaybetemptedtotakeshortcutstoreducecosts. • The returned water not only has added chemicals that facilitate the fracturing but also heavy metals, uranium, and other contaminants that it releases from the shale along with the trapped CH4 (and oil). Without these ‘additives’ the water could be returned to reservoirs or reused, but that is not the case. The water with fracking chemicals can be reinjected for reuse in further fracking, but to avoid the build-up of heavy metals and radioactivity these other ‘additives’ have to be removed and disposed of carefully. This costs money. Even returning the drilling water to reservoirs and other non-fracking uses requireswater decontamination, again a costly process. • Here is where I become wary of human behavior. The easiest and least costly thing to dowith returnedwater is dump it in nearby lakes and streams when no one is watching, which I suspect is occasionally done. Water handling and cleanup costs are amajor operating expense. Contaminants can disturb ecosystems and eventually get Fossil fuels 81